Navigate the the location below in your registry and make the corresponding change.

Key:[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\MSSQLServer]
Value Name: NumErrorLogs
Data Type: REG_DWORD
Data:7 is the default
For More Info go to: http://support.microsoft.com/support/kb/articles/Q196/9/09.ASP 

SQL Server needs to be restarted.

 

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